Mechanical rectifier contacts



July 9, 1957 o. JENSEN MECHANICAL RECTIFIER CONTACTS 6 Shee ts-Sheet 1Filed Aug. 29, 1952 IN VEN TOR. 017a JE/VJ'E/V July 9, 1957 Q JENSEN2,798,909

MECHANICAL RECTIFIER CONTACTS Filed Aug. 29, 1952 6 Sheefis-Sheet 2 INVEN TOR. flrra Java-Ar MM BM {11 imp/W July 9, 1957 o. JENSEN MECHANICALRECTIFIER CONTACTS 6 Sheets-Sheet 3 Filed Aug. 29, 1952 IN V EN TOR. 0pmAw-r July 9, 1957 JENSEN 2,798,909

MECHANICAL RECTIFIER CONTACTS Filed Aug. 29, 1952 6 Sheets-Sheet 4 i Mif aim 2 as IN VEN TOR. drra JEMs/V July 9, 1957 o. JENSEN MECHANICALRECTIFIER CONTACTS 6 Sheets-Sheet 5 Filed Aug. 29, 1952 NTOR. ENS! oar 5I J-rrmF/VEKS July 9, 1957 Q JENSEN 2,798,909

MECHANICAL RECTIFIER CONTACTS IN V EN TOR. firra Jaw/sew UniteMECHANICAL RECTlFlER CONTACTS" My invention relates to mechanicalconverters and r'ectifie'rs', of the type set forth in Patent No.2,693,569 issued November 2, 1954, and is more particularly directed to'a"novel'contact assembly which is readily adjustable to preventbouncing and insure uniform contact engagement and has the furtheradvantage of being readily removable'and replaceable.

A'meclianical rectifier produces direct current by makin'gbridgingcontact between a proper phase of an A. C. system and the associated D.C. system during the time intervalthe particular phase of the A. C.system is capable of delivering energy in the desired direction andbreaking the bridgingcontact when the A. C. phase reverses its voltage"in relationship to the D. C. voltage. This operation is performedsequentially and repeatedly in synchronism with the A. C. frequency.

Mechanical rectifiers utilize a commutating reactor, which is anon-linear or saturable type reactor, to step the current when it passesthrough zero value. This operation is fully described in the abovementioned Patent No. 2,693,569 issued November 2, 1954. During someperiod of each'stepping operation either contact engage ment ordisengagement must be completed. Hence, in a three phase mechanicalconversion unit it is necessary for the contact assembly to make andbreak the circuit 196,000 times per hour. It is therefore apparent thatcontact assembly is a vital component of the conversion unit and must bedesigned to contribute directly to the quality of conversionperformance. Copending application Serial No. 307,024, filed'August 29,1952, is directed to the contact time adjustment for the contactassembly and this application is directed to'the contact assembly perse.

The make and break of the contact assembly isdesigned tooccur during thestepping length of the current so that contact engagement anddisengagement will occur during zero current flow. However, even thoughthere usually is an absenc'e'of current at the time of making andbreaking connections the contact assembly must carry 5,000 amperes andserve through 1,866,000,000 operations for a 360-day period. Impropercontact time adjustmentfor a short period'of time may result in contactpitting, burning and corrosion.

Hence, in order not to further impair proper operation of the converterit is desirable to provide removable and replaceable contact assemblymeans whereby rapid and easy interchange of movable and stationarycontacts is possible. 7

Accordingly, one object of my invention is to provide a compositecompact contact assembly unit which is easily and rapidly removable andreplaceable.

Another object ofmy invention is to provide a mechanical converterwhichlends itself to the interchange of contact assemblies.

A still further object of my invention is toprovide a simple contactassembly unit which contains both the stationary and movable contactsand can be rapidly removed from the converter apparatus.

rates Pat '1 ice Another object'of my invention is to provide a contactassembly which is not connected to the push rod'assembly or contactactuating arm and hence is rapidly and'ea'sily removed Withoutinterfering with the push rod'assembly or adjustment thereof.

Another object of my invention is to provide new and novel contactassembly which is simple in design and easily repaired;

In prior art contact assemblies for mechanical con verters, considerablebouncing and misalignment of the contact occurred.

However, it is imperative that moving contacts seat themselves againstthe stationary contacts without any biasing action, since in the eventof contact biasing, metallic'contact would be made and broken severaltimes during each engagement operation to thereby cause aseries ofarcsto appear, which would cause eventual destruction of the contacts.

, However, with proper alignment of the mating contact surfaces, so thatthe moving contact does not rock when contact is made, bouncing iseliminated. In the contact assembly of my invention a contact adjustingbushingis provided with a'plurality of jack screws which are accessiblewhen the protective hood is removed. With the aid of four D. C.circuits, arranged circumferentially around the movable contact, thejack screws are adjusted until proper alignment of the mating surfacesbetween the stationa'ry and movable contact is accomplished;

Accordingly, a further object of my invention is'to provide a contactassembly for a mechanical converter which is rapidly and easily adjustedto obtainproper alignment of the mating contact surfaces. I

Another object of my invention is to provide a contact assembly wherebya simple and novel structural arrangement permits proper adjustment toeliminate bouncing.

A still further object of my invention is to provide a novel contactassembly which will on seating not bounce or oscillate.

A still further object of my invention is to provide a' novel adjustmentmeans for a contact assembly which will insure'proper alignment betweenthe stationary'contacts and the bridging movable contact.

These and other objects of myinvention will be apparent from thefollowing description When taken in connection with the figures inwhich:

Figure l is a schematic electrical connection diagram of a singlemechanical rectifier unit in which my invention is used.

Figure 2 is a perspective view of the control of the push rod and itseffect on the contact engagement and disengagement.

Figure 3 'is an exploded perspective view showing the contact timeadjustment means.

Figure 4 is an exploded perspective view of the replaceable contactassembly.

Figure 5 is a cross-section view of the assembled replaceable contactassembly of Figure 4.

Figure 6 is a side detailed view of the push rod and associatedremovable and replaceable contact assembly.

Figure 7 is a top view of Figure 6 illustrating the arrangement andassembly of the removable and replaceable contact assemblies.

Figure 8 is a cross-sectional view of the contact assembly of myinvent-ion, similar to Figure 5, showing the position of the contact orsurfaces when they are misaligned.

Figure 9 is a view taken along the line 9-9 of- Figure 5' showing theconnection and position of the D. C. circuit contactors used to adjustthe alignment of the mating contact surfaces.

In Figure 1, the source of alternating current istaken. firom thealternating current lines 10 through the circuit breaker 11 to step downtransformer 12. The source current is then passed through thecommutating reactors 13 to step the current for switching purposes asset forth in Patent No. 2,693,569 issued November 2, 1954. The enclosuremeans 12 and construction of the commutating reactor 13 are more fullydescribed in copending application Ser. No. 301,880, filed July 31,1952, now Patent No. 2,759,128, August 14, 1956.

The current then passes through disconnect switches 14 to the contactconverter 15 which forms the subject of the instant application. Thecontact converter 15 sequentially and repeatedly in synchronism with theA. C. frequency connects the alternating current source buses 1011, b, cto the D. C. load buses 20-21.

The contact converter 15 is bridge connected to permit better use of thepower transformer 12 by doubling the phase operation of the connecterand thereby result in smoother D. C. current and less interference withcommutation facilities as best seen in Figures 2, 6 and 7.

The bridge connected contact converter 15 has two sets of contacts, anegative set 25-30-27 (a-) and a positive set 26-31-28 (a+). The twosets of contacts are off set 180 electrical degrees from each other andthe contacts in either positive or negative set for all the phases a, band c are set 120 apart. The circuit may be supplied with three phasevoltage a, b, c and at one period of time the load current will flowfrom phase a through contact a+ through the load and back over a contactcto 0. During positive commutation between phases a and b, the loadcurrent divides between these two phases by closed contacts a-l and b|-.

For the purpose of simplification, I have shown in Figure 2 theswitching structure which is used at phase a, it being understood thatthe switch apparatus for phases b and c are identical in construction,as seen in Figure 7.

An excited type synchronous motor 40 is energized from the three phasesource voltage a, b, c and drives shaft 41. A cam 42 is integrallyattached to the shaft 41 and therefore driven by the motor 40. The cam42 drives an eccentric 43. The eccentric member 43 is pinned to bellcranks 50-51 by means of pin 52. Since the bell cranks 50-51 arerotatably mounted by bearing 54' on a fixed overlap control shaft 54,the movement imparted to eccentric 43 by cam 42 is a reciprocatingmotion which in turn is imparted to the bell cranks 50-51.

The cross extension arms of the bell cranks 50-51 are connected byrocker arm pins 60-61 which serve as the driving means for push rods 62and 63. The rocker arm pins 60-61 are connected to extending arms 50-51by means of bearing 60-61 so that these pins 60-61 have a rotationalmovement to enable them to maintain constant engagement with the pushrods 62 and 63 as will hereinafter be more fully described.

Push rods 62 and 63 are identical in construction and are shown in theexploded detailed view of Figure 3 and in the detailed side view ofFigure 6. Upward movement of push rod 62 imparted thereto by the rockerarm pin 60 will urge the moveable disc shaped bridging contact 31against the bias of contact spring 81 and thereby disengage it fromengagement with stationary A. C. contact 28 and stationary D. C. contact26.

The structure and operation of the adjustable push rod 62 will best beunderstood from the following description taken in connection with theexploded detailed view of Figure 3 and detailed side view of Figure 6.The push rod 100 is provided with external splines 101 at its lowerportion and an insulated head 102 at its upper portion. The reducedcross-sectional head 103 and the enlarged cross-sectional portion 104 ofinsulating head 102 are sufiiciently small to move through the openingprovided by the space between stationary contacts 26-28 to therebyenable the head 103 to engage the bridging contact ring 31. Hence, whenthe contact rod 100 is moved upward by the rocker arm pin 60 or 61 thereduced cross-sectional portion 103 of the insulating head 102 tionarycontacts 25-27 or 26-28 and portions 103 will engage the lower surfaceof the ring contact 30 or 31 and urge it upward against the bias ofcontact spring or 81 to contact disengaged position.

The insulating material 102 is designed to prevent the movable contact30 or 31 from moving away from the stationary contacts with anoscillatory motion to thereby prevent delayed contact separation whichwould decrease the safety portion of the step.

External splines 101 located at the lower edge of the contact rod meshwith the internal splines 105 of the worm gear 106. Hence, the push rod100 has vertical movement with respect to the worm gear 106 but isrestricted from having rotational movement with respect thereto due tothe mesh of splines 101 and 105. The worm gear 106 as will hereinafterbe more fully explained has no vertical movement and is restricted torotational movement. The worm gear 106 is in mesh with the worm 108which is controlled by the shaft 109 as seen in Figures 2 and 3. Hence,manual rotation of shaft 109 will rotate worm 108. The mesh engagementbetween worm 108 and worm gear 106 will cause worm 109 to rotate theworm gear 106. The mesh engagement of the internal splines 105 of wormgear 106 with the external splines 101 of push rod 100 will cause rotational movement of the push rod 100 due to the rota tional movement ofworm gear 106. As will hereinafter be more fully explained, rotationalmovement of push rod 100 will cause the adjusting screw 110 to threadtoward or away from the push rod 100. Thus, rotation of the worm 108will cause a change in the over-all length of the push rod 62.

The lower portion of push rod 100 is hollow and has a threaded internalportion 111. The internal threads 111 mesh with the external threads ofthe adjusting screw 110. Near the lower portion of the adjusting screw110 is a flange 112 which acts as a stop or rest for the return springcap 113. The return spring 116 is concentric with the adjusting screw110 and is seated at its lower end against the return spring cap 113 andat its upper end against the stationary ledge 107. The lower end of theadjusting screw 110 is provided with a slot 117 that registers with thekey or projection 118 on rocker arm pin 60.

The engagement of projection 118 with slot 117 prevents rotationalmovement of the adjusting screw 110 so that its motion is limited tovertical movement. Thus, during operation of the rectifier thesynchronous motor 40 oscillates the pin 60 through eccentric 43 and bellcranks 50-51 and causes the push rod 100 and attached adjusting screw110 to move as a single unit.

As heretofore noted the rocker pins 60-61 are mounted in bearing 60' and61 of extension arms 50 and 51. The,

projection slot engagement 117-118 between the push rod 62 and rockerpin arm 61 are always in engagement due to the force of return spring116 and the rotational movement of the pins 61 permitted by the bearing61' as seen in Figure 6.

A detailed view of the support mounting and construction of the push rodof Figure 3 is shown in Figure 6.

A housing serves as a guide and vertical support for the push rod 100.Anti-friction bearing 126-127 on the push rod 100 serve as the physicalsupport and guide for the vertical movement of the push rod means 62.The push rod 62 is force fed lubricated by means of oil which is fedinto the area between the rod 100 and the housing 125 through port 128from oil chamber 129. A plurality of oil drip shields 130, 131, 132 areattached to the upper portion of the push rod 100. The oil drip shield130, 131, 132 function in a well known manner to prevent excess oil fromreaching the insulating head 103 and thereby prevent any oil fromreaching the bridging electrical contact 30. Return holes 135 areprovided to return the excess oil through the hollow interior of thepush rod 100. l

The entire push rod assembly 62 of removable contact assembly 71 andhousing means 125 are supported by stationary structures 141 and 142.The lower stationary structure 141 has an extension member 107 whichserves as a bearing support for the worm gear 106 and also as the upperseat for the return spring 116. The extension 145 of stationary supportstructure 141 serves as the support for the housing member 125. Theflange 148 on the housing 125 abuts the stop bushing 149 of support 145.The flange 148 also serves as the upper abutment for the worm gearspring 150, the lower end of this spring resting on the worm gear 106to'continuously urge the gear 106 into engagement with the bushing 107.

Thus, the operation of push rod assembly 62 and 63 is as follows:rotation of the synchronous motor 40 oscillates the bell crank member50-51 about the fixed axis 54'; The sliding engagement between slot andpin 117- I l8 of the push rod and rocker arm pin-60 or 61 plus the guideof housing 125 imparts onlyvertical movement to the push rod 100. Sincethe push rod assemblies 62 and 63" are mounted on opposite ends of thebell crank 50-51, they will be 180 out of phase with each other. At apredetermined position of the upstroke the insulating head 103 willengage the bridging contact 30 and move it upward'against the downwardbias of the 150 pound contact spring 80 and thereby interrupt thecircuit between phase bus 10a at stationary contact 27 and the D. C.negative bus 20 at contact 25. The-bridging contact 30 will remaindisengaged from these stationary contacts 25-27 during the' remainingportion of the upstroke and for a predetermined time or distance of thedown stroke travel'of'the push rod assembly 62.

It will therefore be apparent that for a given R. P. M. of thesynchronous motor 40 the time of contact engagement and disengagementand length of time that the contactsremain engaged and disengaged willbe a function of the elfective length of the push rod assembly 62-63.

As heretofore noted adjustment to modify the length of the individualpush rod assemblies 62'and 63 for phases a, b and c is accomplished bymeans of worm 108 and worm gear 106. The worm gear 106 is continuouslyurged against the bushing 107 by means of hold-down spring 150 and hencehas no vertical motion either independently or with the push rod 100.

Thus, when the rectifier is operating, the spline mesh 105-111 betweenthe worm gear 106 and push rod 100 permits the rocker ann pin 61 tooscillate the push rod assembly 62in a vertical path while the worm gear106 remains stationary. Hence, while the machine is running andunderload, the Worm gear 106 and 108 will remain stationary and thereby beavailable for adjustment to modify the effective length of the push rod62. Rotation of the worm gear 106 by the operators rotation of worm108-109 will cause the push rod 100 to rotate due to mesh therebetweenat splines 105-109. However, since the adjustment screw 110 is keyed tothe rocker arm 60 or 61 and held in tight engagement therewith by meansof return spring 116, the adjustment screw 110 will not be rotated bythe rotation of worm gear 106. Hence, the push rod 100 will be threadedtoward or away from the adjustment screw 100, depending on the directionof rotation of the worm 108, to thereby alter the effective length ofpush rod assembly 62.

As best seen in Figure 7, six contacts may be used in a unit to rectify5,000 amperes. That is, a pair of contact assemblies and push rodassemblies are provided for each phase a, b, c of the source toalternately connect it to the positive and negative buses 20-21 of theload. Thus, each unit switching each phase either to positive ornegative can be independently and individually adjusted to modify thelength of the push rod and achieve proper contact time adjustment.

As fully set forth in copending application Serial No. 212,017 filedFebruary 21, 1951 the mechanical converter will operate at its greatestefficiency when the contact converter 15 causes contact engagement anddisengagement at 'the proper time during the current stepping operationcaused by the commutating'reactor 13. Hence, with the apparatus of myinvention the push rod assembly 62 can be modifiedin length to-adjustfor contact time engagement and disengagement and length of time ofcontact engagement and disengagement to insure maximum efficiency ofoperation.

However, the adjustment or modification of the effective length of pushrod assembly 62 is merely limited to altering the time and length oftime of contact engagement and disengagement and will not eliminatepossible misalignment and resulting'bouncing of the movable contact 31when it is returned to contact engaged position. With the contactassembly-of my present invention adjustment means are provided to-obtain proper mating contact alignment andthereby prevent'bouncing. Thecontact assembly unit 70'is best seen-in Figures 2, 4, 5, 6, 7 and 8.

The 150 pound contactcompression spring 81 has a disc member 121attached to one end thereof and the bridging contact member 31 attachedat the other end thereof. The disc 121 has three grooves 122 drilled inthe upper surface thereof to receive the lower ends of jack screws 1-23.The jack screws 123 are held in the contact adjustment bushing which hasa cylindrical extension 124. The cylindrical extension 124 fits intoopening 125' of the contact block or phenolic housing 126'. The entirecontact unit is housed and protected by the phenolic contact block 126.The phenolic housing 126 is provided with a channel 138 on each of itsfour sides to increase the creepage distance and permit access for thegoverning- D. C. circuit as will hereinafter be more fully described;Openings 128 are provided in top of housing 126 to receive screws 129(see Figure 6) which are threaded into the holes 130 of the pure silverstationary'contacts 26-28 to secure them to the housing 126.

Openings in the top ofphenolic contact block 126 receive andpermif easyaccess to the jack screws 123. Hence, compression spring 81 urges themovable brid ing contact 31 against the stationary contacts 26-23 whichare securedt'o thehousing 126 by means of screws 128 andu'rges thecontact adjustment bushing 120 against the upper portion of the housing126 by force transmitted'through disc 121 and jack screws 123.

All the current carrying members 26-28-31 are made of pure silverthereby providing a constant and extremely small voltage drop. The lossin each contact assembly of a 10,000 ampere machine is of the order 200watts. This slight loss is an important factor in the overall highefficiencyof' the mechanical converter and also has the additionaladvantage of requiring a low capacity cooling system.

The movable bridging contact 31 for a 5,000 ampere converter is 1 /8inches in diameter and the stationary contacts 28 (a) and 26 are oneinch wide and two inches long. Lightness of the moving members offerslittle inertia for rapid action in closing and opening. The small sizeconcentrates the force of the compression spring to aid in firm seatingof the bridging contact 31 over the entire seating area of thestationary contacts 26-28.

The use of a large compression spring 81 plus the concentration offorces permits the use of small contacts.

Adjustment'ofthc alignment of the mating contact surfaces isaccomplished by means of jack screws 123 and governed by the signal D.C. circuit shown in Figures 8 and 9. When the contact surfaces aremisaligned, as best seen in Figure 8, the bridging movable contact 31will come into make position at an angle (dotted lines) with respect tothe stationary contacts and hence will rock and bounce. The jack screwarrangement 123 and the signal D. C. circuits utilized to obtain propercontact alignment will now be "described,

The electrical prongs 151, 152, 153 and 154 and their associatedelectrical connections 155, 156, 157, 158 respectively are clamped ineach of the contact block 126 leakage channels 138 by means of clampmembers 160 as best seen in Figure 9. The electrical prongs 151, 152,153, 154 are spaced from the stationary contacts 28 (a) and 26 as seenin Figure 8 and are positioned circumferentially around the bridgingmovable contact 31. The electrical prongs 151, 152, 153, 154 arepositioned circumferentially around the stationary contact 31 in properposition so that none of the prongs engage the contact 31 when it is inproper alignment with the stationary contact 26-28 as best seen inFigure 9. The four D. C. circuits 155, 156, 157, 158 have identical circuit. Each is provided with a series battery 161, 162, 163, 164 andseries connected lamps 165, 166, 167, 168 as best seen in Figures 8 and9. The D. C. circuits are connected at one end to the electrical feelersor prongs 151, 152, 153, 154 and at the other end 181, 182, 183, 184 areconnected to terminal connector box 170.

All the terminals 181, 182, 183, 184 are connected to the terminal 185to which lead 171 is connected. The lead 171 is electrically connectedto the cylindrical extension 124 of the contact adjustment bushing 120in any suitable manner.

When the bridging contact 31 is misaligned with the stationary contacts26-28 as shown in Figure 8, it will engage the feeler 153 of D. C.circuit 157 but will move further away from feeler 151 of D. C. circuit155. Hence, the D. C. circuit 157 will be energized from battery 162through feeler 153, stationary contact 31, coil spring 81, disc 121,jack screws 123, contactadjustment bushing 121 and its cylindricalextension 124 to lead 171, terminals 185 and 184 of terminal connectorbox 170, to lamp 166 and back to the battery 162. Hence, the lamp 166will be energized as an automatic notice to operator that the movablecontact 31 is too far in the direction of the feeler 153. It will benoted that due to air gap between feeler 151 and bridging contact 31 theD. C. circuit 155 will not be energized and hence the lamp 165 of thatcircuit will not light up. When the bridging contact 31 is too far tothe left and the lamp 166 is energized, as seen in Figure 8, theoperator can adjust the alignment of the mating contacts 26-28-31 byinserting a screw driver in the opening 135 of the contact block 126 andadjust the jack screws 123 until the lamp 166 is de-energized. When boththe lamp 166 and 165 are de-energized, the operator will be assured thatthe bridging contact 31 is in lateral alignment and when the twoindicator lamps 166-168 are extinguished the operator will know that thecontact member 31 is in transverse alignment. That is, when all thelamps 165 are extinguished the bridging contact 31 will be in propermating alignment with the stationarycontacts 26-28.

When this condition is achieved by adjustment of jack screws 123, the D.C. circuitry 155, 156, 157, 158 can be removed by disengaging the fourclamps 160 and detaching lead 171 from the cylindrical extension 124.The contact assembly 70 is now in proper mating alignment and can beplaced in the mechanical rectifier in a manner which will now bedescribed.

The contact mechanism assembly is seen in side view in Figure 6 and intop view in Figure 7.

The D. C. bus bars 20 and 21 extend on both sides and the A. C. bus barsa, 10b, 100 (not shown) are located below the D. C. bus bars. Thecontact assemblies 70, 71 etc., are held in the contact mechanismassembly in contact with the D. C. bar 20 and 21 and A. C. bar 10a bymeans of bracket members 180, 181, 190.

As best seen in Figure 6, the end bracket members 181' 131 are heldsecurely against the top surface of the contact block 126 by means ofbolt and washer 182-183 which are secured to the support bracket 1 85 atthe threaded end 186. The middle bracket 190 is similarly held againstthe contact block 126 by means of bolt and washer 192-193 which threadswith the support flange 195. Coil springs 187 and 197 bias the brackets180-181 and 190 respectively upward to keep these members from fallinginto the space occupied by the contact assemblies -71 when they areremoved.

Removal of the contact assembly 71 is accomplished by loosening thebolts 182-192 sufliciently to enable the brackets -190 to be rotatedfree of the contact assembly 71. Since the force of the brackets 180-190is the only holding and securing means for the contact block, it canreadily and easily be removed from the contact mechanism assembly whenthe brackets 180-190 are rotated out of the Way. The compression springs187-197 will hold the brackets 180-190 in their up position. Afterrepair, the removed contact assembly 71 or another unit can be replacedin the contact mechanism assembly and secured in position by means ofbrackets 180-190.

The end support brackets are constructed with a groove or opening 300between its support legs 301. The openings 300 in support brackets 185are in alignment with the channels 138 of contact blocks 70 and 71. Themiddle support bracket is U-shaped with its center opening in alignmentwith the above mentioned opening 300 and channel 138. Hence, a completeair channel exists from the right hand end, through window or opening300 in end bracket 185, through channel 138 to area surrounding thecontacts 25-30-27, channel 138 on the left on block 71, opening inmiddle support bracket 195, channel 138 on the right of block 70, areasurrounding contacts 23-31-26, channel 138 on the right of block 70 andthrough the opening 300 in the right support bracket 185. Thus, theoperator may observe through window 300, on the left or right of thestructure supporting the contact blocks 70-71, the condition of thecooperating contacts when the converter is running. Hence, the operatorwill have a visual indication of excess sparking at the contacts orundue corrosion or destruction of the silver contacting surfaces.

In summary, my invention relates to a contact assembly unit 70 for amechanical converter-which is easily adjusted to eliminate bouncing ofthe co-operating contacts and to ensure proper alignment of the matingcontacts, is rapidly and easily installed and removed from theconverter, is interchangeable, simple in design and has the advantage ofbeing removable and replaceable.

In the foregoing, I have described my invention only in connection withpreferred specific embodiments thereof. Many variations andmodifications of the principles of my invention, Within the scope of thedescription herein are obvious. Accordingly, I prefer to be bound not bythe specific disclosure herein but only by the appending claims.

I claim:

1. A converter providing a unidirectional current comprising a contactassembly, said contact asssembly comprising a bridging contact and apair of stationary contacts, said bridging contact being a substantiallyrigid member, biasing means to bias said bridging contact intoengagement with said stationary contact, a push rod assembly to etfectcontact disengagement during a step length created by a commutatingreactor, adjustment means tomodify the etfective length of said pushrod, a second adjustment means externally operable to adjust thealignment of said bridging contact with respect to said stationarycontact during operation thereof.

2. A contact'assembly comprising a contact block, a bridging contact,two stationary contacts, a compression spring, a contact adjustmentbushing, and a disc; said bridging contact secured to one end of saidcompression spring and said disc secured to the other end thereof toform a spring assembly, said'stationary contacts secured to said contactblock, said spring assembly positioned between said stationary contactsand said contact adjustment bushing in said contact block, a pluralityof jack screws in threaded engagement with said contact adjustmentbushing, adjustment of said jack screws altering the engagement betweensaid bridging contact and said stationary contact.

3. A contact assembly comprising a pair of cooperating contacts, saidcooperating contacts being substantially rigid members, biasing means tobias said contacts into contact engaged position, externally operableauxiliary adjustment means connected to alter the alignment of saidcooeprating contacts during operation thereof.

4. A contact assembly comprising a pair of cooperating contacts, biasingmeans to bias said contact into contact engaged position, auxiliaryadjustment means connected to alter the alignment of said cooperatingcontacts, said adjustment means comprising a contact adjustment bushingand jack screws, electrical circuitry to indicate when said cooperatingcontacts are improperly aligned, adjustment of said jack screws alteringthe alignment of the mating surface of said cooperating contacts.

5. A converter providing a unidirectional current comprising a contactassembly, said contact assembly having a pair of cooperating contactsbiased into contact engaged position, said cooperating contacts beingsubstan tially rigid members, externally operable auxiliary adjustmentmeans to alter the alignment of said cooperating contacts duringoperation thereof, said contact assembly and said mechanical converteradapted for rapid and easy removal and replacement of said contactassembly from said mechanical converter.

6. In a bridge type contact device for a mechanical rectifier comprisinga first and second contact which are normally in high pressureengagement; said first contact comprising a substantially rigid member,said first contact driven by a push rod assembly for oscillatorymovement to periodically disengage said second contact; externallyoperable adjustment means to alter the alignment of said contacts withrespect to each other during operation of said first contact into andout of engagement with said second contact.

7. A bridge type contact device for a mechanical rectifier comprising amovable contact and a stationary contact which are normally biased intohigh pressure contact engagement; said movable contact driven bysynchronous means and having oscillatory movement to periodicallydisengage and engage said stationary contact; a plurality of auxiliaryadjusting units to correctly center said movable contact with respect tosaid stationary contact; said stationary and movable contact and saidplurality of adjustment means contained within and forming a singlehousing unit which can be removably mounted on a mechanical rectifier.

References Cited in the file of this patent UNITED STATES PATENTS 1,513,059

